3 Answers
3

Windows 7, by default, sets up a schedule to defrag the hard drive. You can modify the schedule by opening Disk Deframenter (type defrag in the search box in the start menu).

Generally, I find that the Disk Defragmenter always shows 0% for all my drives, meaning that Windows is doing its job to keep the drives defragmented. Generally I would say it's not necessary to run a manual defrag, though you may want to run a third-party defrag like MyDefrag if you want to re-organize the files on the disk, like putting large files at the end of the drive.

Personally, I never worry about it and just let the scheduled task do it's thing.

Generally, Windows 7 does a very good job of defragmenting for you in the background. However, if you work with large files or files that grow (or a combination, if you run virtual machines for example), or your hard drive is getting full, then you will need to defragment manually once in a while. I work with virtual machines a lot and due to the size of the drive in my computer, I primarily use expanding disk images, so once my drive was over 70% full I started seeing a lot of fragmentation.

So if you have more than 40% free on your hard drive, don't worry about it, just check it once in a while, but if you have less than that, especially less than 20%, you might have some big fragmentation issues.